Prepare the curd sponge cake. Separate the yolks from the whites. Add the yolks, half of the sugar (50 g), flour, starch, vanilla sugar and baking powder to a bowl. Mix until smooth. Pour in the curd and mix again. The mixture should resemble puree. Whip the whites with the remaining sugar and add them to the dough. Mix.
Cover the baking tray with parchment and spread the dough on it. Bake in the oven preheated to 190℃. Take out the finished sponge cake after 25 minutes. Roll it into a tight roll and leave to cool.
Prepare the filling. Place the cottage cheese, sour cream, sugar, vanilla sugar and jam in a deep bowl. Beat until smooth.
Assemble the roll. Unroll the crust, remove the paper. Grease the surface with the filling and roll again. Place on a serving plate seam side down and refrigerate for 60 minutes.